    section h2{
    	counter-increment: mycounter;
    	counter-reset: subcounter;
    }

    h1,h2{
		text-align: center;
		content: counter(mycounter) '.';
	}

	ul li{
		margin-top: 15px;
		counter-increment: subcounter;
		list-style-type: none;
	}

	ul li:before{
		content: counter(subcounter)'.';
	}
	#container{
		display: flex;
		font-family: 微软雅黑;
		margin-left: 20px;
		margin-right: 20px;
		color: #136062;
	}

	#left-sidebar{
		margin-right: 100px;
		display: flex;
		width: 300px;
		flex-direction: column;
	}

	#left-top{
		flex: 1;
		background-color: #EEBFBF;
	}

	#left-bottom{
		flex: 1;
		margin-top: 20px;
		background-color: #ECECD7;
	}


	#center ul{
		-webkit-column-count: 2;  -webkit-column-gap: 15px; 
        -moz-column-count: 2;     -moz-column-gap: 15px; 
        column-count: 2;          column-gap: 15px; 
        -webkit-animation: myanim 5s 1; /* Chrome, Opera 15+, Safari 5+ */
        animation: myanim 5s 1; /* infinite 循环无限次 */
	}
	/*鼠标移动动画*/
	@-webkit-keyframes myanim {
	  0%   { opacity: 0.0; }
	  50%  { opacity: 0.5; }
	  100% { opacity: 1.0; }
	}


	#left-top,#left-bottom,#center{
		flex: 1;
		padding: 20px;
		box-sizing: border-box;//指定盒的宽度为元素的总宽度
		box-shadow: 5px;
		border-radius: 20px;
	}

/*如何让超链接访问后和访问前的颜色不同且访问后仍保留hover和active效果*/
a:link{color:#03c;}
a:visited{color:#666;}
a:hover{color:#f30;}
a:active{color:#c30;}